Trying to book a very simple domestic one-way trip on Delta metal (SEA-LAS, using skymiles). On the final confirmation page after pressing book the page keeps erroring out with following error. Is this something that I should just sleep on and it will fix itself or some larger issue.

Oh no! We're sorry, <myname>, but we are unable to process your request. Please call the Skymiles Platinum Medallion line at 800-325-1551 for assistance. Customers outside of the 50 United States should contact Delta Reservations for your country.#101727_SMA